1. Field of the Invention
The present invention relates to a display apparatus, and particularly to a display apparatus for outdoor installation.
2. Description of Related Art
Conventionally, flat-panel displays such as a liquid crystal display (LCD) (for example, JP2005-286987 A1) have been widely used as monitors for image displays. However, most of the conventional LCDs are designed for indoor installation, and they are not designed for protection from weather or dust. Therefore, it was difficult to install a conventional LCD outside permanently.
However, in recent years, it has been desired to place LCDs permanently outdoors. This is because the thickness of the displays is small and the LCDs can display high resolution images. Since the thickness of the LCD is small, it can be installed on an outer wall of a building or in narrow places such as a bus stop shelters etc. Further, because the resolution of an LCD is high, can display a clear image even if a display screen is small.
Therefore, in order to protect the liquid crystal display from weather and dust, it was considered to seal a liquid crystal display in a housing.
However, when the LCD is sealed in a housing, heat cannot escape from inside to outside of the housing, so it is unable to cool the LCD by air naturally. Thus, temperature of the liquid crystal display is increased by the heat generated by its operation or sunlight. When the temperature of the liquid crystal display increases, the function of the liquid crystal degrades. As a result, it may not be able to display an image on the display screen (which is called a “black out”).